On 6/22/21 4:01 PM, Matthias Kretz wrote:
On Tuesday, 22 June 2021 21:52:16 CEST Jason Merrill wrote:
For alias templates, you probably want the attribute only on the
templated class, not on the instantiations.
Oh good point. My current patch does not allow the attribute on alias
templates. Consider:
template <class T, class U>
struct X {};
template <class T>
using foo [[gnu::diagnose_as]] = X<T, int>;
I have no idea how this could work. I would have to set the attribute for an
implicit partial specialization (not that I know of the existence of such a
thing)? I.e. X<int, int> would have to be diagnosed as foo<int>, but X<int,
float> would have to be diagnosed as X<int, float>, not foo.
So if anything it should only support alias templates if they are strictly
"renaming" the type. I.e. their template parameters must match up exactly. Can
I constrain the attribute like this?
Yes. You can check that with get_underlying_template.
Or you could support the above by putting the attribute on the
instantiation with the TEMPLATE_INFO for foo<A> rather than a simple name.
Jason
